With the development of communication technologies, various methods for wireless communication have been used so as to overcome inconvenience of wired communication always requiring lines at the time of communication Among those, an IEEE (Institute of Electrical and Electronic Engineers) 802.11 based WLAN has been in the limelight recently.
Provided that all the stations belonging to BSS are established with a single channel (BSS channel) for communicating with an access point (AP) in IEEE 802.11 standard [IEEE 802.11 WC, Part 11 Wireless LAN MAC and PHY specification, IEEE Standard, August 1999.], all the traffics generated from a station (STA) are transmitted to destinations via the AP. Herein, the basic service set (BSS) means a set of stations communicating through any one channel and the WLAN may perform the communication in one BSS unit. The station, which is a member of one BSS, means an apparatus that can perform the wireless communication. In the IEEE 802.11 standard, an inter-station distance sufficiently approximates each other, but twice transmission from a transmitting station to the AP and from the AP to a receiving station is performed in the case of the inter-station traffic generated in the BSS, such that the wireless channel resources may be wasted twice.
In order to overcome the inefficiency and directly perform the transmission of the inter-station traffic within the BSS, the IEEE 802.11e standard [IEEE 802.11e WG, Part 11: IEEE Standard for Information technology Telecommunications and information exchange between systems Local and metropolitan area networks Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements.] defines a direct link setup. The DLS defined herein, which is a subject a QAP (QoS-enabled AP), sets an inter-station direct link call setup and then, directly transmit and receive the traffic generated for a predetermined time between two stations, thereby increasing the efficiency the wireless channel resources twice.
However, the DLS defined in the IEEE 802.11e required new functionality for the AP, such that the replacement of the existing distributed APs is was needed. This was not welcomed in the market, and several years after the standard was established, WLAN equipment manufacturers were still not using the DLS. Therefore, methods of allowing the final stations to set the direct link other than the method of setting the inter-station direct link using the QAP according to the related art have been proposed. One of the methods is disclosed in H. Yoon, J W Kim and R Hsieh, “iDLS Inter-BSS direct link setup in IEEE 602.11 WLANs,” Communications and Information Technologies, 2007 ISCIT '07 International Symposium on, vol., no., pp. 1015-1020, 17-19 Oct. 2007.